The foliicolous lichen Gallaicolichen pacificus exhibits unique goniocystangia-like structures named peltidiangia and peltidia. Its taxonomic classification within the Ascomycota has been unclear due to the absence of ascomata and lack of molecular data. Here we clarify the phylogenetic affinities of Gallaicolichen pacificus by analyzing mitochondrial small subunit ribosomal RNA (mtSSU) sequences obtained from specimens collected in New Caledonia. Ascomata and ascospores of G. pacificus, previously unknown, are described and illustrated for the first time. The results from the molecular and morphological analyses clearly indicate that Gallaicolichen pacificus belongs to the Porinaceae and is closely related to Porina guianensis. This is a remarkable extension of the already known, wide morphological diversity of thalli and diaspores produced within this family.

Evidence for fire affecting the solubility of metals in Fe oxide-rich Oxisols of the Koniambo Massif of New Caledonia is presented. Acid-dissolution studies showed that Ni, Al and Cr are substituted for Fe in the structure of the Fe oxides. Thermal dehydroxylation of goethite under oxidizing conditions led to the formation of hematite and to the migration of some of these metals towards the surface of hematite crystals as indicated by their enhanced release during the early stage of dissolution. Dehydroxylation of goethite under reducing conditions led to the formation of hematite and maghemite. Nickel and Al were released preferentially during the early stages of dissolution whereas Cr was not released preferentially and may be uniformly incorporated within maghemite and hematite crystals. These results have significance to the mineral-processing industry, to geochemical exploration and to the availability of these metals to plants growing on burnt soils.

The green turtle Chelonia mydas is a large marine turtle present in tropical and subtropical seas of the Atlantic, Pacific and Indian Oceans. It is categorized as Endangered on the IUCN Red List based on the trend of nesting populations at 32 sites, of which only three are in the Pacific Ocean. New Caledonia is a sui generis overseas territory of France in the south-west Pacific Ocean c. 1,210 km east of Australia. The presence of green turtles in New Caledonian waters is known, although the main nesting sites are far from the main island, on remote uninhabited islands. Since 1988 field missions to these remote reefs, namely d'Entrecasteaux, Bellona and Chesterfield, have collected data to quantify the nesting of green turtles in New Caledonia. For the first time we analyse the data collected during these missions. D'Entrecasteaux, Bellona and Chesterfield Reefs host a large nesting colony of green turtles, with the upper credible estimate of nesting activities reaching 150,000 nesting tracks in some years. These numbers exceed the estimated number of green turtle activities in the Pacific. The trend of the number of nesting activities is stable and has the same relationship with the Southern Oscillation Index as observed at Australian nesting sites. Our recommendations for the French authorities are to continue monitoring these populations, collect new demographic parameters and ensure the protection of these remote reefs, which should be considered a national treasure for New Caledonia.

The upper canopy of some rain forests in New Caledonia is dominated by single species. These monodominants are commonly secondary species, their dominance not persisting without disturbance. We tested whether dominance is associated with efficient uptake and use of nutrients (N, P and K), comparing between seedlings of monodominants (Nothofagus spp., Arillastrum gummiferum and Cerberiopsis candelabra) and 14 subordinates, grown in a nursery house. We also tested whether this trend applies more broadly to shade-intolerant trees that regenerate episodically (ER species) versus shade-tolerant trees that regenerate continuously (CR species). In the sun treatment, monodominants had higher photosynthetic nutrient-use efficiency and productivity for N and K, and uptake efficiency for N, P and K, than subordinates; ER species had higher photosynthetic nutrient-use efficiency for N, P and K, and uptake efficiency for N and P, than CR species. Uptake efficiency and productivity per nutrient mass were uncorrelated across species, yet Nothofagus spp., A. gummiferum and C. candelabra combined high levels of both traits for N, and Nothofagus spp. and A. gummiferum combined moderate to high levels for P, in sun-grown seedlings. This trait combination may contribute substantially to competitiveness and post-disturbance dominance on these nutrient-poor soils.

Carbon and nitrogen stable isotopes were used to describe an estuarine mangrove food web in New Caledonia, SW Pacific. Isotopic values were measured for all components of the ecosystem, from various organic matter (OM) sources to predators. Primary producers showed δ13C values from −32.29‰ (Bruguiera gymnorhiza) to −24.67‰ (mouth particulate organic matter), whereas δ15N values ranged from 1.48‰ (Avicennia marina) to 10.17‰ (Eichomia crassipes). Two potential organic matter sources, i.e. the mangrove species and E. crassipes, appeared not to be directly used by consumers although were indirectly entering the food web through particulate and sedimentary organic matter pools (POM and SOM). Overall, invertebrates showed C-depleted and N-depleted values compared with fish, highlighting their lower trophic level. The highest trophic levels in this estuarine mangrove were represented by carangids (δ15N of 11.24‰ for Caranx sp. and 10.81‰ for Carangoides fulvoguttatus) and gerrids (δ15N of 10.42‰ for Gerres filamentosus). Two main pathways of organic matter were identified from sources of OM to end-members, i.e. from estuarine POM and SOM toward gerrids and from marine POM towards carangids. The food chain comprised three or four trophic levels, depending on the pathway of organic matter. The position of some consumer species within the reconstructed food web might imply that an important source of organic matter was probably missing, i.e. microphytobenthos. Despite an obvious connection, the role of river inputs as potential drivers of mangrove food web dynamics appeared important only during the wet season.

Araucaria goroensis R.R.Mill & Ruhsam sp. nov., a new monkey puzzle species from New Caledonia, is described and illustrated with photographs from the field and from herbarium specimens. Previously confused with Araucaria muelleri, it is more similar to A. rulei. It is distinguished from the latter species by its larger leaves, microsporophylls without a shouldered base, and shorter female cone bracts. It occurs in a very limited area of south-east New Caledonia, where its existence is threatened by nickel mining. Using the guidelines of the International Union for Conservation of Nature, we propose an assessment of Endangered for the new species and reassess Araucaria muelleri also as Endangered. A key to the seven species in the ‘large-leaved clade’ of New Caledonian species of Araucaria is given. The name Eutassa latifolia de Laub. is synonymised with Araucaria muelleri, and the recent typification of the latter name by Vieillard 1276 is rejected. Detailed reasoning is given for these nomenclatural acts.

A pollen record from Lake Xere Wapo, southeast New Caledonia, is the longest continuous terrestrial record to be recovered from the tropical southwest Pacific and reveals a series of millennial scale changes in vegetation over the last ∼130,000 yr. A comparison of the Lake Xere Wapo record with the key northeast Australian record of Lynch's Crater reveals regional patterns of change. From ∼120,000 to ∼50,000 yr ago the vegetation around Lake Xere Wapo alternated between rainforest and maquis with fire an important disturbance factor. In the last 50,000 yr fire is almost absent from the record and the vegetation assumes a character unprecedented in the preceding 100,000 yr, dominated by Dacrydium and Podocarpus pollen. The most compelling aspect of the comparison with Lynch's Crater is that the much-discussed Araucaria decline at around 45,000 yr ago in northern Queensland is matched by a similar decline in the Lake Xere Wapo record.

Lithostratigraphic and palynological analysis of two cores recovered from the ‘Grand Lac’ (New Caledonia), combined with 35 14C AMS dates, yields a paleoenvironmental record spanning the last 2000 yr. The lithology is represented mainly by clayey or laminated layers. A catastrophic event, which is marked by very coarse deposits, occurred probably between ca 1070–960 cal yr B.P. and possibly is associated with an unusually severe La Niña event. Before and after this event, a similar combination of the two main sediment types is recorded. The repeated alternation of laminated and clayey layers is interpreted as the response to local hydrologic forcing, which may reflect a shift from relatively wet to relatively drier conditions, respectively. Variable amount of micro-charcoal is detected all along the profile. Without additional evidence, notwithstanding the initial local human settlement documented since ca 2900 14C yr B.P., micro-charcoal occurrence and variability cannot be linked directly to an anthropogenic origin. No distinct palynological zonations in relation to the lithology are observed, and the vegetation changes may only represent minor transitions across environmental limits.

Multiproxy analysis of three littoral cores from western New Caledonia supports the hypothesis that the main controlling factors of environmental changes are sea-level change, ENSO variability and extra-tropical phenomena, such as the Medieval Warm Period (MWP) marked by a tendency for La Niña-like conditions in the tropical Pacific. The record starts during the late Holocene sea-level rise when the terrestrial vegetation indicated wet and cool conditions. The site was a coastal bay definitely transformed into a freshwater swamp at around 3400 cal yr BP, after the rapid drawdown of sea level to its current level. Sediments and foraminiferal assemblages indicated subsequent episodes of freshwater infillings, emersion or very high-energy conditions, likely related to climatic changes and mostly controlled by ENSO variability. Between 2750 and 2000 cal yr BP, relatively dry and cool climate prevailed, while wetter conditions predominated between ca. 1800 and 900 cal yr BP. The Rhizophoraceae peak between ca. 1080 and 750 cal yr BP, coeval with the MWP, may indicate a global phenomenon. Microcharcoal particles present throughout the record increased after 1500 cal yr BP, suggesting an anthropogenic source. From ca. 750 cal yr BP the appearance of current type of vegetation marks the human impact.

Unlike most tropical Pacific islands, which lie along island arcs or hotspot chains, the Loyalty Islands between New Caledonia and Vanuatu owe their existence and morphology to the uplift of pre-existing atolls on the flexural forebulge of the New Hebrides Trench. The configuration and topography of each island is a function of distance from the crest of the uplifted forebulge. Both Maré and Lifou are fully emergent paleoatolls upon which ancient barrier reefs form highstanding annular ridges that enclose interior plateaus representing paleolagoon floors, whereas the partially emergent Ouveapaleoatoll rim flanks a drowned remnant lagoon. Emergent paleoshoreline features exposed by island uplift include paleoreef flats constructed as ancient fringing reefs built to past low tide levels and emergent tidal notches incised at past high tide levels. Present paleoshoreline elevations record uplift rates of the islands since last-interglacial and mid-Holocene highstands in global and regional sea levels, respectively, and paleoreef stratigraphy reflects net Quaternary island emergence. The empirical uplift rates vary in harmony with theoretical uplift rates inferred from the different positions of the islands in transit across the trench forebulge at the trench subduction rate. The Loyalty Islands provide a case study of island environments controlled primarily by neotectonics.

Some species-rich secondary forests in New Caledonia have a monodominant canopy. Here we investigate growth and biomass allocation traits that might explain single-species’ dominance of these post-disturbance stands, and their later decline in the absence of large-scale disturbance. Seedlings of 20 rain-forest trees were grown in two light treatments in a nursery house. In the sun treatment, monodominants grew faster (56.7 ± 1.4 mg g−1 wk−1) than subordinates (40.2 ± 2.6 mg g−1 wk−1). However, some episodically regenerating (ER) subordinates had high growth rates similar to those of monodominants. In the shade treatment, monodominants and subordinates had similar growth rates (33.7 ± 2.6 and 34.0 ± 1.9 mg g−1 wk−1 respectively). Notably, monodominants in both sun and shade treatments had lower root mass fraction (0.29 ± 0.02 and 0.27 ± 0.02 g g−1 respectively) than subordinates (0.39 ± 0.02 and 0.37 ± 0.02 g g−1). Fast growth in sunny conditions is probably imperative for these relatively shade-intolerant ER monodominants. In field conditions, high shoot mass fraction combined with efficient root performance may facilitate faster growth in monodominants competing with other ER species in sunlit sites. Slower growth in shade may contribute to loss of dominance over time in undisturbed forests.

Based on separately obtained and analyzed molecular data and within the framework of a global revision of the family Trypetheliaceae, 21 new species are described, from the Neotropics and tropical Asia, in the genera Architrypethelium (1), Astrothelium (15), Bathelium (1), Nigrovothelium (1), Trypethelium (1), and Viridothelium (2), namely: Architrypethelium lauropaluanum Lücking, M. P. Nelsen & Marcelli sp. nov., differing from A. hyalinum in the perithecia immersed between coarse thallus verrucae and in the additional ascospore septa; Astrothelium aurantiacocinereum Lücking, Naksuwankul & Lumbsch sp. nov., differing from A. aeneum in the prominent, well-delimited, trypethelioid pseudostromata and the absence of pigment on the thallus surface, as well as in the barely lichenized thallus; A. carassense Lücking, M. P. Nelsen & Marcelli sp. nov., differing from A. purpurascens in orange, K+ red pseudostroma pigment and the slightly larger ascospores; A. cryptolucens Lücking, M. P. Nelsen & N. Salazar sp. nov., differing from A. carrascoense in the inspersed hymenium; A. fijiense Lücking, Naksuwankul & Lumbsch sp. nov., differing from A. cinereorosellum in the presence of lichexanthone on the well-delimited pseudostromata and in the slightly shorter ascospores; A. laevithallinum Lücking, M. P. Nelsen & Marcelli sp. nov., differing from A. endochryseum in the smooth thallus; A. leucosessile Lücking, M. P. Nelsen & Aptroot sp. nov., differing from A. phlyctaena in the conspicuous, sessile pseudostromata; A. macrostomoides Lücking, M. P. Nelsen & Benatti sp. nov., differing from A. macrostomum in the larger ascospores; A. megacrypticum Lücking, M. P. Nelsen & N. Salazar sp. nov., differing from A. longisporum in the single-spored asci and larger ascospores; A. nicaraguense Lücking, M. P. Nelsen & T. Orozco sp. nov., differing from A. gigantosporum in the smaller ascospores; A. norisianum Lücking, M. P. Nelsen & Aptroot sp. nov., differing from A. sepultum in the distinct, well-delimited pseudostromata; A. obtectum Lücking, M. P. Nelsen & Benatti sp. nov., differing from A. nigrocacuminum in the smaller ascospores; A. sordithecium Lücking, M. P. Nelsen & Marcelli sp. nov., differing from A. leucothelium in the inspersed hymenium and the absence of lichexanthone from the thallus surface outside the pseudostromata; A. subendochryseum Lücking, M. P. Nelsen & Marcelli sp. nov., differing from A. endochryseum in the absence of pigment in the pseudostromata and the lateral thallus cover of the pseudostromata; A. subinterjectum Lücking, M. P. Nelsen & Jungbluth sp. nov., differing from A. obtectum in the smaller pseudostromata and smaller ascospores, and from A. interjectum in the diffuse pseudostromata and smaller ascospores; Bathelium porinosporum Lücking, M. P. Nelsen & Gueidan sp. nov., differing from other Bathelium species in the 3-septate, euseptate ascospores; Nigrovothelium bullatum Lücking, Upreti & Lumbsch sp. nov., differing from N. tropicum in the bullate thallus; Trypethelium tolimense Lücking, Moncada & M. Gut. sp. nov., differing from T. xanthoplatystomum in the absence of a yellow-orange pigment on the pseudostromata and the K+ yellow (not K+ red) medullary pigment; Viridothelium tricolor Lücking, M. P. Nelsen & N. Salazar sp. nov., characterized by black perithecia with a lateral ostiole immersed in white pseudostromata strongly contrasting with the surrounding brown thallus, in combination with 2-spored asci and large, muriform ascospores; and V. vonkonratii Lücking, Naksuwankul & Lumbsch sp. nov., differing from V. virens in larger ascospores and mostly solitary ascomata. All species are illustrated and their taxonomy and phylogenetic relationships are discussed. ITS barcoding sequences are reported for five specimens of Bathelium porinosporum.

The living species of the genus Retrophyllum C.N. Page (Podocarpaceae) are revised. A key to the six species recognised is given. Retrophyllum filicifolium (N.E.Gray) R.R.Mill comb. nov. from New Guinea and the Moluccas is recognised as a species distinct from R. vitiense (Seemann) C.N. Page, which is restricted to material from Fiji and the Solomon Islands. Additional characters are given by which to separate Retrophyllum piresii (Silba) C.N. Page (Brazil) from R. rospigliosii (Pilg.) C.N. Page (Andes). The six species fall into three species-pairs that differ in reproductive characters: one pair in Papuasia and Melanesia, a second on New Caledonia and a third in South America. In the New Caledonian species-pair, the adult leaves are flattened in four ranks with only minimal heterofacial twisting, whereas in the species-pair inhabiting Fiji, New Guinea and neighbouring areas, as well as the pair inhabiting South America, the adult leaves are arranged in two ranks with significant heterofacial twisting. The names Podocarpus filicifolius N.E.Gray and Nageia minor Carrière, respectively the basionyms of Retrophyllum filicifolium and R. minus, are lectotypified, and the typification of Nageia minor comprehensively discussed in an appendix. Adult female epitypes are additionally designated for Podocarpus filicifolius, which was originally based on juvenile foliage of Retrophyllum mixed with a detached seed of Nageia wallichiana, and for Nageia minor, which Carrière described on the basis of sterile material. Two other appendices provide a list of accepted names and synonyms, and a list of exsiccatae. Illustrations and distribution maps are provided for each species.

Several monodominant rain-forest trees in New Caledonia have population size structures suggesting establishment following large-scale disturbance, with eventual replacement by shade-tolerant species predicted in the absence of future disturbance. Links of dominance and population dynamics to leaf-level photosynthesis were investigated in seedlings of 20 tree species from these forests, grown in experimental sun and shade conditions. In particular, we tested whether episodically regenerating (ER) species, including monodominants, have higher assimilation rates at high irradiances and lower tolerance of shade than continuously regenerating species (CR). ER species had higher maximum net assimilation rates (Amax-area) in sun plants (9.6 ± 0.4 μmol m−2 s−1) than CR species (6.2 ± 0.3 μmol m−2 s−1) and high plasticity, typical of shade-intolerant species, but monodominant species did not differ from other ER species. CR species had leaf-level traits consistent with shade tolerance, including lower dark respiration rates (Rd-area = 0.47 ± 0.03μmol m−2 s−1; Rd-mass = 7 ± 1 nmol g−1 s−1) than ER species (Rd-area = 0.63 ± 0.06 μmol m−2 s−1; Rd-mass = 11 ± 2 nmol g−1 s−1) in shade plants. Hence leaf-level assimilation traits were largely consistent with regeneration patterns, but do not explain why some shade-intolerant species can achieve monodominance.